The present invention relates to a computer vision inspection system and more particularly to a computer vision inspection system for sheet metal parts.
In manufacturing operations, a wide variety of sheet metal parts are required and need to be inspected to determine whether they are within acceptable error tolerances. Different parts may have different error tolerances associated therewith requiring different inspection criteria. Past methods of inspection have included the statistical sampling of parts from a manufacturing run and the determination of the occurrence of error for the entire run based on such a sample. Obviously this method has drawbacks in that a defective part may slip past the inspection process.
Inspection has typically involved selecting a part to be inspected and manually comparing the part with a template representing the desired shape. Such an inspection method is labor intensive and requires that a number of templates be maintained on hand to facilitate inspection. Other inspection methods merely involve comparison with engineering drawings.
While machine vision inspection systems have heretofore been designed to inspect large quantities of identical parts on an assembly line, in some industries manufacturing flow is not suited to such an arrangement. Machine vision systems as heretofore designed are not suited to a relatively low part quantity inspection wherein it is desired to inspect a wide variety of parts and to switch between part inspection types with relative ease.
A method which has been used to avoid massive template storage involves storing template information in a computer and generating a new inspection template when needed by means of a plotter and a mylar plotting surface. When a part is to be inspected, a new template is generated on mylar, but once the inspection is complete the mylar template is thrown away. Such a system has drawbacks in that it is wasteful and slow, with additional operations and personnel being required to generate the various templates.
Automated manufacturing processes often generate sheet metal parts from digital data created by a computer aided design process and there may be no template as such readily available. It would be desirable to provide an inspection method which quickly inspects parts using the design data from a computer aided design representation of a part.